InferencePool: Finalize InferencePool.ExtensionRef.PortNumber

[capri-xiyue]

What happened:
#1366 (comment) changed InferencePool.ExtensionRef.PortNumber to be non-pointer as // +kubebuilder:validation:Minimum=1

// PortNumber defines a network port.
//
// +kubebuilder:validation:Minimum=1
// +kubebuilder:validation:Maximum=65535
type PortNumber int32

reading the API spec (When unspecified, implementations SHOULD infer a default value of 9002 when the Kind is Service), seems like pointer is needed here and the "0" usually means all ports instead of not setting. Wondering whether it is a little bit weird here to use "0" as a not set indicator

There are three options

1. don't use kube-api linter convention and use pointer type here

2. Keep it as what it is and the implementation should infer a default value of 9002 when the Kind is Service and the port number is 0 as 0 means unset here

3. Use

// +optional
PortNumber *PortNumber `json:"portNumber,omitempty"`

// PortNumber defines a network port.
//
// +kubebuilder:validation:Minimum=0
// +kubebuilder:validation:Maximum=65535
type PortNumber int32

Nil means unset and 0 means all ports, but do we need to support all ports here?

I feel option 1 is better, see more context here #1387

What you expected to happen:

How to reproduce it (as minimally and precisely as possible):

Anything else we need to know?:

Environment:

• Kubernetes version (use kubectl version):
• Inference extension version (use git describe --tags --dirty --always):
• Cloud provider or hardware configuration:
• Install tools:
• Others:

[capri-xiyue]

Another option is to check we can disable kubeapi linter for some tagrtline that we really want to use pointer

[capri-xiyue]

Based on the slack discussion, I will create a PR to configure KubeAPI Linter to enforce the upstream optional field guidance for built ins, so every optional is a pointer independent of the zero value being valid or not (match https://github.com/kubernetes/community/blob/master/contributors/devel/sig-architecture/api-conventions.md#serialization-of-optionalrequired-fields)

[capri-xiyue]

/assign

[capri-xiyue]

Based on the slack discussion, I will create a PR to configure KubeAPI Linter to enforce the upstream optional field guidance for built ins, so every optional is a pointer independent of the zero value being valid or not (match https://github.com/kubernetes/community/blob/master/contributors/devel/sig-architecture/api-conventions.md#serialization-of-optionalrequired-fields)

Will take the approach after the community reaches a agreement #1387 (comment)